Antiplatelet Medications Overview

Antiplatelets

• Aspirin (ASA): Inhibits cyclooxygenase, reducing platelet aggregation. Indications include acute coronary syndrome (ACS), myocardial infarction (MI) prophylaxis, and transient ischemic attack (TIA). Contraindications include aspirin or non-steroidal anti-inflammatory drug (NSAID)-induced asthma, and gastrointestinal (GI) bleeding. Side effects include bleeding, abdominal bleeding/ulcers, and bronchospasm. Aspirin is given orally (PO) and rectally (PR).

• Glycoprotein IIb/IIIa inhibitors: Reversibly inhibit the binding of fibrinogen and von Willebrand factor to GPIIb/IIIa receptors, impairing hemostatic plug formation. Indications include high-risk patients with acute coronary syndrome (ACS) and urgent cardiac surgery. Contraindicated in active bleeding. Side effects include bleeding and thrombocytopenia. Administered intravenously (IV). Rarely used due to availability of dual antiplatelet therapy (DAPT) and P2Y12 meds.

• P2Y12 inhibitors: Bind to P2Y12 adenosine diphosphate receptors, reducing platelet activation and aggregation. Indications include acute coronary syndrome (ACS), coronary artery disease (CAD) and prevention of thromboembolic events, including acute ischemic stroke (TIA). Contraindicated in active or intracranial bleeding. Side effects include bleeding, intracranial hemorrhage and dyspnea. Administered orally.

Anticoagulants

• Heparin/Unfractionated Heparin (UFH): Activates antithrombin III, stopping prothrombin and preventing fibrinogen-to-fibrin conversion. Indications include prevention and treatment of deep vein thrombosis (DVT)/pulmonary embolism (PE). Contraindicated in active bleeding, and should be used with caution in patients with spinal or epidural injections. Side effects include bleeding and heparin induced thrombocytopenia (HIT). Administered intravenously (IV) or subcutaneously (SQ).

• Low molecular weight heparin (LMWH): Inhibits thrombin and factor Xa. Prevention and treatment of DVT/PE, and risk reduction in atrial fibrillation. Contraindicated in active bleeding, and should be used with caution in patients with spinal or epidural injections. Side effects include bleeding and HIT. Generally given subcutaneously (SQ).

• Fondaparinux: Selectively inhibits factor Xa. Indications include prevention/treatment of DVT/PE. Contraindicated in active bleeding and renal impairment. Side effects include bleeding. Administered subcutaneously (SQ).

• Warfarin (Coumadin): Inhibits vitamin K-dependent coagulation factors. Indications include prevention and treatment of DVT/PE, prevention of stroke in patients with cardiac valve replacement, risk reduction in atrial fibrillation. Contraindicated in pregnancy (except in mechanical valve situations) and active bleeding. Side effects include bleeding, abdominal pain, alopecia, and tissue necrosis. Administered orally.

Direct Oral Anticoagulants (DOACs)

• Apixaban, Rivaroxaban: Inhibits factor Xa and reduces thrombin generation and thrombus formation. Prevention/treatment of DVT/PE, atrial fibrillation (especially after joint surgery), and coronary interventions. Contraindications include active bleeding and major bleeding risk. Caution in patients with spinal or epidural catheters. Side effects include bleeding, abdominal pain and nausea. PO administration.

• Dabigatran: Inhibits thrombin directly preventing fibrinogen from cleaving to fibrin. Different dosing than other DOACs. See slide 25 of provided information.

• Bivalirudin: Directly inhibits thrombin. Used mainly in percutaneous coronary interventions (PCI) and patients with heparin-induced thrombocytopenia (HIT). Contraindicated in active bleeding. Side effects include bleeding. Administered intravenously (IV).

Non-Pharmacological Prophylaxis

• Ambulation: Important to prevent venous thromboembolism.
• Graduated Compression Stockings/Intermittent Pneumatic Compression Devices (IPCD): Improve blood circulation to decrease risk.
• Inferior Vena Cava Filters (IVC): Used as a last resort when medical interventions fail in preventing blood clots from reaching the lung.

Heparin-Induced Thrombocytopenia (HIT):

• Characterized by thrombocytopenia, timing of platelet fall after heparin therapy, thrombosis, and other causes of thrombocytopenia. Treatment involves stopping heparin therapy and using an alternative anticoagulant.

Other Medications (See Pages 5,6,7 for details)

A variety of other medications are discussed in the provided texts including: ACE inhibitors, Angiotensin II Receptor Blockers (ARBs), Diuretics, Calcium Channel Blockers, Nitrates